Bone marrow exists in hollow spaces within bones and acts as a nursery for many of the cellular components of peripheral whole blood. Among the blood cells produced in bone marrow are erythrocytes (red blood cells), platelets (clotting cells) and leukocytes (white blood cells). These blood cells all develop from the so called “stem cells,” which are cells in the bone marrow that are capable of both propagating additional stem cells as well as developing into all three types of blood cells.
Stem cells, pluripotential cells and blasts in the bone marrow are very active in cell division to continuously replace blood cells. Without adequate blood cell replacement, patients can develop anemia, clotting disorders and failed immune responses. The extensive cell division activity of the stem cells makes the bone marrow particularly sensitive to therapeutic treatments which are directed at quickly dividing cancer cells, such as chemotherapy and radiation therapy. As a result, it is not unexpected that cancer patients undergoing intensive therapies can sustain life-threatening damage to their bone marrow. Other disease indications may give rise to patients sustaining severe damage to their bone marrow, radiation sickness, aplastic anemia, and cancer metastasis to bone marrow. Bone marrow replacement is often the only available cure for some of these maladies.
Replacement bone marrow can come from the patient (autologus marrow) or from a donor (allogeneic marrow). Bone marrow is typically harvested from large bones near the skin, such as the iliac crest of the hip or the sternum, by pushing a stout needle through the hard outer bone cortex to capture a core sample of bone marrow tissue. A vacuum (i.e., less than atmospheric pressure) is applied to the needle bore to aspirate fluids from the bone including blood and loose marrow cells. Before such a bone marrow harvest can be infused in to a recipient patient, stem cells are typically separated from the connective tissue of the core sample and the mature peripheral blood cells in the aspirated fluid. In order to obtain enough bone marrow to supplement or reconstitute a functional bone marrow in a patient, the puncture and aspiration procedure is generally repeated many times, e.g., 25-50 times in each iliac crest. General anesthesia is commonly used to reduce the emotional stress and pain of the repeated punctures; however, infliction of multiple wounds compound the bone pain, bruising and infection potential of the procedure.
In view of the above, a need exists for a device and methods to obtain bone marrow from a smaller number of bone punctures. Benefits can also be realized from methods that provide a higher ratio of stem cells compared to connective tissue and peripheral blood cells. The present invention provides these and other features that will be apparent upon review of the following.